Can I increase the number of worker threads the parallel toolbox uses?

I'm running 2013b on a 16-core SuperMicro workstation (Ubuntu 12.04) as well as an 8-core ASUS Zenbook (Windows 8) and in both cases, the number of threads used is half the number available. maxNumCompThreads gives the same numbers, 8 and 4 respectively. For either system, but especially the workstation, is there a way to get the OS to give Matlab more threads? I don't see any reason to leave the extra cores idle.

Answer 1

[Shashank Prasanna]

Intel CPUs with hyper-threading give the appearance that a computer has twice as many cores than it actually has. The additional number of cores you see are essentially Virtual cores. Even if you were able to spawn more threads than 8 on the first machine, you would most likely see performance degradation due to threads fighting each other for cpu time. Take a look at the Hardware Considerations section of this link:

http://www.mathworks.com/products/matlab/choosing_hardware.html

[Matthew Phillips]

Hmm, I can manually control the # of threads with my C++ apps, I will test this and see if it results in actual degradation or improvement. But as far as the prospect of getting more threads in Matlab is concerned, it looks like you have answered my question.

[Walter Roberson]

It is possible to use the hyperthreads if you want to. There is a configuration file that you would need to edit; I do not recall which one.